One of the components of a circuit that steps up or steps down voltage is a reactor. For example, Patent Literature 1 discloses a reactor that is used in a converter installed in a vehicle such as a hybrid vehicle. The reactor includes a coil made of a wound wire, an annular magnetic core where the coil is disposed, a case storing a combined product made up of the coil and the magnetic core, and a sealing resin with which the case is filled. Terminal fittings are respectively attached to the end portions of the wire structuring the coil. The coil is supplied with power from an external apparatus such as a power supply via the terminal fittings. Generally, the reactor is used as being fixed to a cooling base for cooling the coil and the like, which produce heat when being energized.
The representative case is a die casting product made of aluminum. The case is used as being fixed to the cooling base to serve as a heat dissipation path for dissipating heat from the coil and the like.